Tried the following in the mongo shell

> use foo
switched to db foo
> db.f.save(

{"name":"c:\a\b\c"}

);
> db.f.save(

{"name":"c:\\a\\b\\c"}

);
> db.f.find();

{ "_id" : ObjectId("4edd38551252ee52efdc0ed3"), "name" : "c:a\bc" } { "_id" : ObjectId("4edd38621252ee52efdc0ed4"), "name" : "c:\\a\\b\\c" }

>

The handling of backslashes within strings does not seem to be consistent. The first example removes some of them without doing anything to the following characters. The second example fails to use "
" as an escape for '\'.